This application is an improvement over applicant's assignee's U.S. Enno H. Page Patents No. 4,298,051 issued Nov. 3, 1981, No. 4,413,666 issued Nov. 8, 1983, and No. 4,766,943 issued Aug. 30, 1988; Dybala et al U.S. Pat. No. 4,529,028 issued July 16, 1985, and applicant's U.S. Pat. No. 4,867,225 issued Sept. 19, 1989 and applicant's copending application Ser. No. 07/374,649 filed June 30, 1989, all of which deal with die casting cores and their coatings and their respective compositions and methods of producing the same.
Furthermore, sand cores for castings in which the sand is bound together by a polymerized resin are known according to Lirones U.S. Pat. No. 3,321,005 issued May 23, 1967, Robins U.S. Pat. No. 3,639,654 issued Feb. 1, 1972, and Horton U.S. Pat. No. 3,688,832 issued Sept. 5, 1972, the latter of which even mentions rinsing a core with solvents.
However, none of the above references discloses all of the specific steps and specific compositions invented and disclosed herein.